Genetic variation in the gene methylenetetrahydrofolate reductase (MTHFR) is associated with a mild elevation of homocysteine and with cardiovascular disease. The applicant makes a case for this genetic variance being the single most important genetic risk factor for atherosclerosis. Data supporting his view is presented in the extensive publications by Dr. Rozen, the consultant on this research proposal, and others. The literature does not appear to be as convincing for a correlation between MHTFR genotype and cardiovascular disease. The ultimate goal of this proposal is to use a single gene based test to identify individuals with variant forms of MTHFR. The applicant argues that these patients can effectively be treated with folate and B12 with routine monitoring of blood and urine homocysteine. MTHFR is a cytoplasmic flavoprotein that is involved in the biochemical pathway to recover methionine, an essential amino acid. The specific aims proposed are: (1) to determine the allele frequency and haplotype of variances in MTHFR in a group of 270 diverse individuals, (2) using the sample, to identify variances in genes on related pathways for homocysteine metabolism, and (3) to develop and validate diagnostic tests for the clinical assessment of genetic variances. Dr. Rozen has cloned and characterized the MTHFR gene. She is listed as a collaborator on this grant proposal and Variagenics has obtained an exclusive license to the MTHFR gene. The investigator will use a proprietary method to detect variances and determine haplotypes. In this technique the T4 Endo VII resolvase cleaves DNA duplexes at "heteroduplexes" formed by hybridizing wild-type DNA and that from a sample containing an insertion or deletion. These cleavage products will be analyzed by either gel electrophoresis, automated sequencing or capillary gel electrophoresis. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE